Electron Microscope Evidence for a Membrane Around the Core of the Ubisch Body in<i>Lilium</i>(Liliaceae)

Clément, Christophe; Audran, Jean‐Claude

doi:10.1080/00173139309429995

Cited by 13 publications

(8 citation statements)

References 8 publications

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“…4H, arrow). This orbicule ultrastructure in Dioscoreales is very similar to that found in Lilium (Liliales; Clément and Audran 1993). Orbicules are significantly larger in Narthecium than in Dioscorea, ca.…”

Section: Orbicule Ontogeny and Ultrastructuresupporting

confidence: 57%

“…In both Narthecium and Dioscorea, the orbicules have an electron-lucent core that is the remains of the pro-orbicule, and this does not appear to increase in size during orbicule development. Around this core is the main electron-dense orbicule layer, referred to as the orbicule wall (Clément and Audran 1993), and outside this is a very electron-dense peripheral layer that can be seen only at high magnifications ( fig. 4H, arrow).…”

Section: Orbicule Ontogeny and Ultrastructurementioning

confidence: 99%

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Comparative Pollen Development in Dioscoreales

Schols¹,

Furness

Merckx

et al. 2005

International Journal of Plant Sciences

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Pollen and orbicule ontogeny in representatives of three genera of Dioscoreales-Narthecium ossifragum Huds. (Nartheciaceae), Tacca artocarpifolia Seem. and Tacca chantrieri André (Dioscoreaceae), and Dioscorea communis (L.) Caddick & Wilkin (Dioscoreaceae)-is described and illustrated using LM, SEM, and TEM. The main difference is in microsporogenesis, which is successive in Narthecium Huds. and simultaneous in Tacca J.R. & G. Forst. and Dioscorea L. This is reflected in the tetrad configuration but not in the apertures: Narthecium and Tacca are monosulcate, while Dioscorea has two equatorial apertures. Other features of pollen development are similar in all three genera. Exine development starts at the proximal pole, and during the tetrad stage, the exine remains thicker at this pole. Intine development begins before mitosis. A conspicuously channeled intine forms beneath the aperture(s) in all three genera, and in Tacca it also occurs in nonapertural regions. After mitosis, the generative cell is situated at the proximal pole in all genera. Orbicules are present in Narthecium and Dioscorea but not in Tacca, although it has a secretory tapetum. In the tetrad stage, pro-orbicules appear on the tapetum in Narthecium and Dioscorea, and pro-sporopollenin is consequently deposited to form the orbicule wall.

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Section: Orbicule Ontogeny and Ultrastructuresupporting

confidence: 57%

Section: Orbicule Ontogeny and Ultrastructurementioning

confidence: 99%

Comparative Pollen Development in Dioscoreales

Schols¹,

Furness

Merckx

et al. 2005

International Journal of Plant Sciences

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“…Similar white line tailshaped extensions are observed in Platanus acerifolia (SuarezCervera et al 1995); in Rondeletia odorata these are apparent in the late free microspore stage (Huysmans 1998, El-Ghazaly et al 2001, and in Pinus sylvestris in metaphase-I to prophase-II (Rowley & Walles 1993). The material surrounding the pre-orbicules gave positive reactions for glycoproteins (PTA) and can be interpreted as a glycocalyx positioned upon the membrane delimiting the pre-orbicule (Clément & Audran 1993c) (Fig. 5B -C).…”

Section: Tapetum and Orbicule Developmentmentioning

confidence: 70%

A histological study of microsporogenesis inTarenna gracilipes(Rubiaceae)

Vinckier

Smets

2005

Grana

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We studied the microsporogenesis in Tarenna gracilipes (Hayata) Ohwi, with special attention to the mode of exine deposition and tapetum development. We based this research on light (LM), scanning electron (SEM) and transmission electron microscopic (TEM) observations of developing anthers of T. gracilipes, from the microspore mother cell stage towards anther dehiscence. Evidence is supplied that the microsporogenesis in T. gracilipes can be considered as simultaneous. Columellae, foot layer and tectum develop in a fibrillar matrix. Similar with earlier studies in Rubiaceae species, a single white line formed near the plasmalemma in the extra-apertural region. The developing endexine dilated into several white line centered lamellae at the apertures. An annulus is formed around the inner surface of each pore. In the mature intine two strata can be distinguished. At the apertures thick onci are formed protruding through the apertures thereby forming papillae, a common feature in Rubiaceae. In Rubiaceae species amoeboid as well as secretory tapeta are reported. In T. gracilipes it is shown that the tapetum cells possess in all developmental stages characteristics of the secretory type. During microsporogenesis the tapetum cytoplasm undergoes considerable changes which may indicate cycles of hyperactivity. Sporopollenin deposition on the pre-orbicules is mediated by white lines showing correlations with endexine, annulus and columellae ontogeny. These findings corroborate the idea that orbicule wall development can represent a model to study sporopollenin deposition. At anther dehiscence Ca-oxalate crystals are released out of the ruptured septum cells into the locule, providing a possible visual signal for pollinators.

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“…It has been suggested that orbicular ontogenesis starts during meiosis (Clément and Audran, 1993), but the timing of pro-orbicule formation varies slightly among species, ranging from the early stages of meiosis through to the microspore release stage (Steer, 1977). Orbicules are a characteristic feature of plants with a secretory tapetum (Huysmans et al, 1998) and this includes rice.…”

Section: Changes In the Tapetummentioning

confidence: 99%

Cellular organisation in meiotic and early post-meiotic rice anthers

Mamun

Cantrill

Overall

et al. 2005

Cell Biology International

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We have used fluorescent, confocal laser and transmission electron microscopy (TEM) to examine cellular organisations, including callose (1,3-beta-glucan) behaviour, in meiotic and early post-meiotic rice anthers. These features are critical for pollen formation and provide information to better understand pollen sterility caused by abiotic stress in rice and other monocotyledonous species. Among organelles during meiosis, abundant plastids, mitochondria and nuclei of the anther cells show distinctive features. Chloroplasts in the endothecium store starch and indicate a potential for photosynthetic activity. During meiosis, the middle layer cells are markedly compressed and at the tetrad stage are either vacuolated or filled with degenerating electron-opaque organelles. Viable mitochondria, stained with Rhodamine 123, are seen in the endothecium and tapetum, but the mitochondria in the middle layer are not stained during meiosis. The radial walls of the tapetum are disorganised and degenerating, indicating the formation of a syncytium; pro-orbicules are located at the locular walls at the tetrad stage. Immunohistochemical studies show that the sporogenous cells are entirely enveloped by a thick callosic layer at early meiosis. Cell plate callose was assembled in a plane between the dyad cells. In the tetrads, however, callose formed only at the centre, showing that the tetrad microspores are not enveloped but separated by callose walls. Thick, undulating electron-opaque walls around the tetrads indicate the beginning of exinous microspore wall differentiation.

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Electron Microscope Evidence for a Membrane Around the Core of the Ubisch Body inLilium(Liliaceae)

Cited by 13 publications

References 8 publications

Comparative Pollen Development in Dioscoreales

Comparative Pollen Development in Dioscoreales

A histological study of microsporogenesis inTarenna gracilipes(Rubiaceae)

Cellular organisation in meiotic and early post-meiotic rice anthers

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